Reinforcing asbestos-cement sheets and apparatus for use therein



Dec. 11, 1951 F. L. NASH &

REINFORCING ASBESTOS-CEMENT SHEETS AND APPARATUS FOR USE THEREIN Filed Aug. 18, 1948 3 Sheets-Sheet 1 %;7 g TTO/QNEK Dec. 11, 1951 F. NASH 2,578,580

REINFORCING ASBESTOS-CEMENT SHEETS AND APPARATUS FOR USE THEREIN Filed Aug. 18, 1948 5 Sheets-Sheet 2 i INVEN TOR.

Dec. 11, 1951 F. 1.. NASH REINFORCING ASBESTOS-CEMENT SHEETS AND APPARATUS FOR USE THEREIN 3 Sheets-$heet 3 Filed Aug. 18, 1948 JNVENTOR. fiw/z L/7/7d/d Mas/7 Patented Dec. 11, 1951 REINFOR-CING ASBESTOS-CEMENT SHEETS AND APPARATUS FOR USE THEREIN Frank Lennard Nash, Widnes, England, assignor to Turners Asbestos Cement Company Limited, Rochdale, England, a British company Application August 18, 1948, Serial No. 44,828 In Great Britain October 20, 1947 3 Claims.

The present invention relates in general to the internal reinforcement of objects, and it deals more particularly with the reinforcement of asbestos cement sheets or the like.

The common way of making asbestos cement or like sheets is to coat a rotating cylinder with the asbestos cement or other material in a moist state. The most common form of machine including such a rotating cylinder is of the Hatschek type in which successive laminations of the moist material are transferred from a carrier band to the cylinder (which is commonly known as a forming bowl). When the laminations have built up to the desired thickness a cut must be made parallel to the axis so that the laminated covering on the forming bowl can be detached from it and removed as a sheet. A groove is commonly made along the bowl and may be called the parting-off line, a knife being run along this groove by the operator to make the cut.

The cutting of a sheet of asbestos cement while it is still in a plastic state is a simple matter. However, the sheets must often be internally reinforced and the reinforcement is introduced while the material is still on the forming bowl, being inserted between two laminations. To cut a reinforced sheet is not simple, as the reinforcement commonly consists of metal, and it is found to be practically impossible to out through a reinforced sheet while the asbestos-cement is still plastic. It is at this stage, however, that it is desirable to cut any sheet to its final size.

Each length of reinforcement preferably takes the form of a number of parallel wires extending circumferentially around the rotating cylinder. Wm. H. Rooksby application Serial No. 673,791, filed June 1, 1946, describes a form of apparatus for feeding reinforcing wires lengthwise to the rotating cylinder of a machine of the Hatschek type so that they are located on the cylinder in predetermined positions in relation to the parting-off line. More particularly, each wire is wrapped around the cylinder with its opposite ends disposed in spaced-apart relationship on either side of the parting-off line; thus, the asbestos cement sheet can be out from the cylinder without having to cut through the wires.

Now the length of the finished sheet is determined by the diameter of the forming bowl, and when it is desired to vary the length the forming bowl must be changed for another of a different diameter. It is inconvenient to have to provide a large number of forming bowls to allow sheets of different lengths to be made, and short sheets are sometimes made by using a forming bowl large enough to produce a long sheet and then cutting this long sheet into shorter lengths. In practice a long sheet is generally cut into two short sheets and to provide a large variety of different lengths of sheet, the lengths of these two short sheets may vary considerably in relation to one another. For instance, if a forming bowl is used which gives a sheet 12 feet long this sheet may be out in half to give two lengths of 6 feet each or it may be cut to give sheets of 5 feet and '7 feet or yet again it may be cut to give sheets of 8 feet and 4 feet.

It is an object of the present invention to provide apparatus for forming long reinforced sheets which may easily be cut in shorter lengths.

Another object is to provide apparatus for forming a sheet of the character disclosed in the aforementioned Rooksby application Serial No. 673,791, except that the continuity of the reinforcing wires is interrupted along one or more lines extending crosswise of the sheet intermediate its ends thereby to facilitate cutting of the sheet into short lengths.

Further objects and advantages of the invention will be apparent from the following description of the preferred embodiment of the invention. In this description reference is made to the accompanying drawings in which:

Figure 1 is a side elevation of the preferred apparatus,

Figure 2 is a plan view of the apparatus shown in Figure 1, and

Figure 3 shows diagrammatically the positions of the reinforcing wires on the rotating cylinder and in the finished sheet,

Figure 4 is an enlarged detail View taken along the line 44 of Figure 1, in the direction of the arrows,

Figure 5 is a detail view of the cam operated switches and the associated manual control therefor, and.

Figure 6 is a sectional elevation taken along the line 66 of Figure 5 in the direction of the arrows.

In the apparatus shown, an endless felt band I, carrying a layer of asbestos cement slurry passes over a roller 2 into contact with a rotary cylinder or forming bowl 3. The asbestos cement is transferred to the forming bowl at the point where the band I passes through the nip between the form ing bowl and a pressure roller 4, and as the operation proceeds successive laminations are built up on the bowl. When the desired thickness has been attained the coating is removed from the bowl as the result of a cut made by a knife guided and inclined at a slightly greater angle to the horizontal, so that the two sets of tubes converge towards the forming bowl, being supported by brackets 8 and 9. The tubes have funnel-shaped mouths H! and are arranged in alignment with two further sets of tubes H and i2 which also have funnel-shaped mouths l3 and are supported by brackets H3 and HE.

A reinforcing wire of the appropriate length is placed in each of the tubes H and I2 and extends into the corresponding tube 6 or 1, being prevented from passing beyond the end of the tube by plates l6 and ii closing the ends of the tubes 6 and l respectively. These plates slide in guides l8 and Iii and are provided with ports 26 corresponding to the ends of the tubes. The plates are pulled into the position in which the ports register with the ends of the tubes by wires 2| and 22 against the action of tension springs 23 and 2 1 which return the plates to the position of non-register when the tension is released from the wires. The wires 2% and 22 pass over pulleys 25 and 26 and 27 and 28 respectively and are attached to the armatures 2s and 36 of solenoids 3| and 32. Thus when the solenoids are energised the armatures are attracted and apply tension to the wires 21 and 22 to move the plates it and ll into the position in which the ports register with the ends of the tubes and as soon as the solenoids are deenergised the plates return to the position of non-register.

When wires are in position in the tubes each is exposed over a short axial length corresponding to the gap between the sets of tubes 5 and l l or i and 52 as the case may be. Each wire is acted on frictionally at this point by a pair of rollers 33 and 34 or 35 and 3% which are driven from an electric motor 3? and serve to urge the wire downwards along the tube. The operation of these rollers is exactly analogous to that of the rollers 23 and 24 shown in Figures 5 and 6 of application Serial No. 673,791.

As soon as either solenoid 3| or 32 is energised to move the corresponding plate into the registering position the wires in the corresponding set of tubes are fed forward under the influence of the friction rollers, being guided by a sheet-metal extension-piece 38 on the end of the tubes so that they wrap smoothly around the forming bowl 3 and lie in the positions shown in Figure 3.

Each of the solenoids is energised by way of an electrical circuit which includes a cam-operated switch. A swivel 39 controls the solenoid 3| and a switch 40 the solenoid 32. The switches are carried on a lever arm ll pivoted at 42 and are actuated by cams 43 and iii carried on an extension 45 of the main shaft of the forming bowl. In its free position the arm 4i hangs so that the switches are clear of the respective cams, but it may be moved by the operator into a position (shown dotted in Fig. 5) in which it is in contact with a stop 46 and in which the switches may be actuated by the projections on the respective cams.

The cam 43 which serves to initiate the feed of the wires in the set of tubes 6 is set on the shaft to time the feeding so that the leading ends of the wires lie close to the parting-off line 5. Since, whatever the relative lengths of the two shorter sheets into which the sheet is to be out, the end of the reinforcement must lie close to the end of the sheet, the setting of the cam 43 will be constant and will not require alteration. The position of the ends of the second set of wires in the tubes 1 will, however, depend on the relative lengths of the two shorter sheets and the angular position of the cam t l must therefore be adjusted accordingly.

In use the operator allows the coating to build up until it has reached approximately half the desired thickness. He then moves the lever arm 4| into contact with the stop to bring the surfaces of the cams 43 and M into contact with the respective switches. The two sets of reinforcing wires are then fed to the forming bowl at the appropriate instants and wrap smoothly around it. The coating then continues to build up on top of the reinforcing wires until the final thickness is reached, when the coating is removed from the forming bowl in the usual manner.

Although the invention is primarily useful in its application to the manufacture of asbestoscement sheets, it may also be applied to the manufacture of sheets from any simiiar materiai which will set rigid from a plastic state, contain-.

ing for example other fibres or another binding agent.

It will also be understood that the various features of the apparatus described are by way of example only and may be modified to suit any particular conditions. For instance, the switches 39 and till instead of being movable away from the surfaces of their respective cams i3 and 44 may be fixed in contact with the surfaces so that the switches are closed for each revolution of the forming bowl. In this case an additional switch is included in each of the solenoid circuits, the two switches being operated by a common handle, enabling the operator to close both switches together in that revolution of the forming bowl in which it is desired to insert the reinforcement.

Having thus described my invention, I claim:

1. In combination with a rotary mandrel for winding up a web of plastic material to form a multi-layer tube, means for storing a plurality of sets of reinforcing wires so they are disposed longitudinally of the advancing web with one end of the wires adjacent the point where the web reaches the mandrel, means urging the wires axially toward said point, a plurality of barriers each normally preventing the advance of one set of wires toward said point, and a trip mechanism operable in any selected revolution of the mandrel for removing the barriers one after another during said revolution thereby to. cause the separate sets of wires to advance successively at predetermined intervals during said revolution, said trip mechanism including a member rotatable with said mandrel having a plurality of circumferentially spaced trip elements, means adjacent said member responsive to the passage of said trip elements, and apparatus controlled by said last named means for removing a different barrier with the passage of each trip element.

2. In combination with a rotary mandrel for Winding up a web of plastic material to form a multi-layer tube, means for storing a plurality of sets of reinforcing wires so they are disposed longitudinally of the advancing web with one end of the wires adjacent the point where the web reaches the mandrel, means urging the wires axially toward said point, a plurality of barriers each normally preventing the advance of one set of wires toward said point, and a trip mechanism operable in any selected revolution of the mandrel for removing the barriers one after another during said revolution thereby to cause the separate sets of wires to advance successively at predetermined intervals during said revolution, said trip mechanism including a member rotatable with said mandrel having a plurality of circumferentially spaced trip elements, a pivotal arm located adjacent said member having an operative and inoperative position with respect to said member, a plurality of control elements carried by said arm responsive to the pasage of said trip elements when said arm is in the operative position with respect to said member, and apparatus controlled by said control elements adapted to remove a different barrier with the passage of each trip element. 1

3. In combination with a rotary mandrel for Winding up a web of plastic material thereby to form a multi-layer tube which is adapted subsequently to be cut from the mandrel along a parting-off line parallel to the axis of the tube, means for storing a plurality of sets of reinforcing wires so they are disposed longitudinally of the advancing web with one end of the wires 6 adjacent the point where the web reaches the mandrel, means urging the wires of each set axially toward said point, a plurality of barriers each normally preventing the advance of oneset of wires toward said point, a member rotatable with said mandrel having a plurality of circumferentially spaced trip elements, mecha nism operative in any selected revolution of the mandrel and responsive to the motion of said trip elements to remove the barriers one after 7 another during said revolution thereby to cause the separate sets of wires to advance successively and be wrapped around the mandrel between superposed layers of the tube during a single revolution of said mandrel, and means operable at will to select the revolution at which said mechanism removes said barriers.

FRANK LENNARD NASH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 728,804 Lindberg May 19, 1903 800,839 Watson Oct. 3, 1905 1,771,749 Eisenhardt July 29, 1930 1,831,050 Von Rottenburg Nov. 10, 1931 2,373,672 Ferla Apr. 17, 1945 

1. IN COMBINATION WITH A ROTARY MANDREL FOR WINDING UP A WEB OF PLASTIC MATERIAL TO FORM A MULTI-LAYER TUBE, MEANS FOR STORING A PLURALITY OF SETS OF REINFORCING WIRES SO THEY ARE DISPOSED LONGITUDINALLY OF THE ADVANCING WEB WITH ONE END OF THE WIRES ADJACENT THE POINT WHERE THE WEB REACHES THE MANDREL, MEANS URGING THE WIRES AXIALLY TOWARD SAID POINT, A PLURALITY OF BARRIERS EACH NORMALLY PREVENTING THE ADVANCE OF ONE SET OF WIRES TOWARD SAID POINT, AND A TRIP MECHANISM OPERABLE IN ANY SELECTED REVOLUTION OF THE MANDREL FOR REMOVING THE BARRIERS ONE AFTER ANOTHER DURING SAID REVOLUTION THEREBY TO CAUSE THE SEPARATE SETS OF WIRES TO ADVANCE SUCCESSIVELY AT PREDETERMINED INTERVALS DURING SAID REVOLUTION, SAID TRIM MECHANISM INCLUDING A MEMBER ROTATABLE WITH SAID MANDREL HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED TRIP ELEMENTS, MEANS ADJACENT SAID MEMBER RESPONSIVE TO THE PASSAGE OF SAID TRIP ELEMENTS, AND APPARATUS CONTROLLED BY SAID LAST NAMED MEANS FOR REMOVING A DIFFERENT BARRIER WITH THE PASSAGE OF EACH TRIP ELEMENT. 